ICOS and obesity due to melanocortin 4 receptor deficiency: Pretherapeutic infiltration of CD8+ T cells in tumor tissues has been demonstrated to be correlated with the response to immunotherapy in tumor patients.38 A previous study revealed that in NSCLC patients receiving nivolumab, high numbers of peripheral CD8+ T cells lacking costimulatory receptors (CD28, ICOS, OX40) at baseline are associated with the response.39 Our findings suggest that obesity may not affect the function of peripheral CD8+ T cells through the ICOS pathway.